Venous cannula

ABSTRACT

A process for inducing cardioplegic arrest of a heart in situ in a patient&#39;s body, comprising maintaining the patient&#39;s systemic circulation by peripheral cardiopulmonary by-pass, occluding the ascending aorta through a percutaneously placed arterial balloon catheter, venting the left side of the heart, and introducing a cardioplegic agent into the coronary circulation. This procedure readies the heart for a variety of surgical procedures that can be performed percutaneously through lumina in the catheter. An aortic catheter for use in the process is also described.

This is a continuation of Ser. No. 08/614,634, filed Mar. 13, 1996, nowabandoned, which is a division of Ser. No. 08/427,384, filed Apr. 24,1995, now U.S. Pat. No. 5,725,496 which is a divisional of applicationSer. No. 08/159,815, filed Nov. 30, 1993, which issued on Jul. 18, 1995as U.S. Pat. No. 5,433,700.

FIELD OF THE INVENTION

The present invention relates to a method for inducing cardioplegicarrest in a heart and to catheters for use in that method.

BACKGROUND OF ART

The use of extracorporeal cardiopulmonary by-pass for cardiac supporthas become well established. This use has, however, involved mediansternotomy or less commonly thoracotomy with all of the trauma thatnecessarily accompanies such a major surgical procedure.

The present invention contemplates, at least in its preferredembodiments, the possibility of effective ascending aortic occlusion,cardioplegia, venting, right heart deflation and topical cooling inassociation with extracorporeal cardiopulmonary by-pass all withoutnecessitating a median sternotomy or other thoracic incision.

DISCLOSURE OF THE INVENTION

In a first aspect the present invention consists in a method forinducing cardioplegic arrest of a heart in situ in a patient's body,comprising the steps of:

(a) maintaining systemic circulation with peripheral cardiopulmonaryby-pass;

(b) occluding the ascending aorta through a percutaneously placedarterial balloon catheter;

(c) introducing a cardioplegic agent into the coronary circulation; and

(d) venting the left side of the heart.

The method according to the present invention may be carried out onhumans or other mammalian animals. The method is of particularapplicability in humans as it allows an alternative approach to openheart surgery and the development of closed cardioscopic surgery. Themethod according to the invention enables a percutaneous by-pass systemto be associated with cardioplegia, venting and cooling of the heartwhich subverts the need for median sternotomy. This may, in turn, reducethe complications of the surgery.

The maintenance of the systemic circulation involves establishing acardiopulmonary by-pass. The blood may be drawn into the by-pass merelyby positioning a percutaneous catheter into the right atrium and/or intoone or both of the vena cavae through which venous blood may be drawnfrom the heart into an extracorporeal pump oxygenator. In more preferredembodiments of the invention a single catheter with two inflatablecuffs, or two separate catheters, each with an inflatable cuff areintroduced into the vena cavae to occlude them adjacent to their rightatrial inlets. This allows isolation of the right atrium and allowsblood to be drawn from the vena cavae into the by-pass system. There isalso preferably provision for percutaneous communication via onecatheter with the right atrium to allow infusion of saline into theright atrium. This infusion has the advantage that it allows the heartto be cooled and improves visual acuity within the right heart allowingdirect cardioscopic examination and/or intervention.

The catheter used to decompress the right atrium and to draw blood intothe by-pass is preferably introduced through the femoral vein bypercutaneous puncture or direct cut down. If other than simple venousdrainage is required catheters with inflatable cuffs, as describedabove, are placed preferably such that an inflatable cuff of the cannulais positioned within each of the inferior (suprahepatic) and superiorvena cavae. There is preferably a lumen in the cannula acting as acommon blood outlet from the vena cavae leading to the pump oxygenator.A separate lumen is preferably used to infuse saline between the twoinflated cuffs into the right atrium. If, alternatively, separatecatheters are used to occlude each of the inferior and superior venacavae then the cannula for the inferior vena cavae is preferablyintroduced percutaneously from the femoral vein and that for thesuperior vena cavae is introduced percutaneously through the jugular orsubclavian vein.

The ascending aorta is preferably occluded by a balloon catheterintroduced percutaneously through the femoral artery. This catheter mustcarry adjacent its tip an inflatable cuff or balloon of sufficient sizethat upon being inflated it is able to completely occlude the ascendingaorta. The length of the balloon should preferably not be so long as toimpede the flow of blood or other solution to the coronary arteries orto the brachiocephalic, left carotid or left subclavian arteries. Aballoon length of about 40 mm and diameter of about 35 mm is suitable inhumans. The balloon is of a cylindrical shape to fully and evenlyaccommodate the lumen of the ascending aorta. This maximizes the surfacearea contact with the aorta, and allows for even distribution ofocclusive pressure.

The balloon of the catheter is preferably inflated with a salinesolution to avoid the possibility of introducing into the patient an airembolism in the event that the balloon ruptured. The balloon should beinflated to a pressure sufficient to prevent regurgitation of blood intothe aortic root and to prevent migration of the balloon into the rootwhilst not being so high as to cause damage or dilation to the aorticwall. An intermediate pressure of the order of 350 mmHg has been proveneffective in trials.

The aortic catheter is preferably introduced under fluoroscopic guidanceover a suitable guidewire. Transoesophageal echocardiography canalternatively be used for positioning as has been described withreference to the venous catheter. The catheter may serve a number ofseparate functions and the number of lumina in the catheter will dependupon how many of those functions the catheter is to serve. The cathetercan be used to introduce the cardioplegic agent, normally in solution,into the aortic root via one lumen. The luminal diameter will preferablybe such that a flow of the order of 250-500 ml/min of cardioplegicsolution can be introduced into the aortic root under positive pressureto perfuse adequately the heart by way of the coronary arteries. Thesame lumen can, by applying negative pressure to the lumen from anoutside source, effectively vent the left heart of blood or othersolutions. It may also be desirable to introduce medical instrumentsand/or a cardioscope into the heart through another lumen in thecatheter. The lumen should be of a diameter suitable to pass afibre-optic light camera of no greater than 3 mm diameter. It ishowever, preferable that the diameter and cross-sectional design of theinternal lumina is such that the external diameter of the catheter inits entirety is small enough to allow its introduction into the adultfemoral artery by either percutaneous puncture or direct cut-down.

The oxygenated blood returning to the body from the by-pass system maybe conveyed into the aorta from another lumen in the cannula carryingthe balloon. In this case the returning blood is preferably dischargedfrom the catheter in the external iliac artery. In another embodiment ofthe invention, and in order to reduce the diameter of the cathetercarrying the balloon, a separate arterial catheter of known type may beused to return blood to the patient from the by-pass system. In thiscase a short catheter is positioned in the other femoral artery toprovide systemic arterial blood from the by-pass system. The control-endof the catheter, i.e., that end that remains outside of the body, shouldhave separate ports of attachment for the lumina. The catheter lengthshould be approximately 900 mm for use in humans.

The cardioplegic agent may be any of the known materials previouslyknown to be useful, or in the future found to be useful, as cardioplegicagents. The agent is preferably infused as a solution into the aorticroot through one of the lumina of the aortic catheter.

In another aspect the present invention consists in a catheter for usein occluding the ascending aorta comprising an elongate tube having oneor more continuous lumina along its length, an inflatable cuff isdisposed about the tube adjacent one end thereof, the cuff being of sucha size that upon being inflated it is able to occlude the ascendingaorta of a patient.

The catheter and method according to the present invention can be usedto induce cardioplegic arrest and may be used in a number of surgicalprocedures. These include the following:

1. Coronary artery revascularisation such as:

(a) angioscopic laser introduction or angioscopic balloon angioplastycatheter into the coronary arteries via one lumen of the aorticcatheter; or

(b) thoraco dissection of one or both of the mammary arteries withrevascularisation achieved by distal anastomoses of the internal mammaryarteries to coronary arteries via a small left anterior thoracotomy.

2. Secundum--type arterial septal defect repair such as by:

(a) "Closed" cardioscopic closure, or

(b) Closure as an "open" procedure via a mini-right thoracotomy.

3. Sinus venosus defect repairs similar to 2 above.

4. Infundibular stenosis relief by cardioscopic techniques.

5. Pulmonary valvular stenosis relief by cardioscopic techniques.

6. Mitral valve surgery via a small right thoracotomy

7. Aortic stenosis relief by the introduction of instrumentation via alumen in the aortic catheter into the aortic root.

8. Left ventricular aneurysm repair via a small left anteriorthoracotomy.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter given by way of example are preferred embodiments of thepresent invention described with reference to the accompanying drawingsin which:

FIG. 1 is a schematic partly cut-away representation of a patients hearthaving percutaneous catheters placed therein for carrying out the methodaccording to the present invention;

FIG. 2 is a similar view to FIG. 1 showing the aortic catheter inposition but including an angioscope and a left ventricular ventingcannula introduced into the aortic root and left ventricle respectively,via separate lumina within the aortic catheter;

FIG. 3 is a front elevational view of part of the vascular system of apatient showing, inter alia, the aortic balloon catheter positioned inthe ascending aorta via the femoral artery;

FIG. 4 is a side elevational view of the control end of the aorticcatheter according to the present invention;

FIG. 5 is a partly cut away side elevational view of the balloon end ofthe catheter of FIG. 4 in an inflated condition;

FIG. 6a is a cross-sectional view of the catheter of FIG. 4 intermediatethe control end and the balloon end;

FIG. 6b is an alternative cross-sectional arrangement of the lumina inthe catheter of FIG. 4;

FIG. 7 is a cross-sectional view through the balloon end of the catheterof FIG. 4;

FIGS. 8a and 8b show schematically two alternative arrangements to thecatheter shown in FIG. 4;

FIGS. 9a and 9b show schematically two alternative catheter arrangementsfor the isolation of the right atrium and venous drainage.

BEST METHOD OF CARRYING OUT THE INVENTION

The heart 10 of FIGS. 1 and 2 is positioned in the living body of apatient and is accessed percutaneously.

In order to induce cardioplegia in the heart while maintaining thepatient it is necessary to divert the patients blood circulation throughan extracorporeal cardiopulmonary by-pass system 8. This is achieved byisolating the heart 10 on both the venous and arterial sides usingappropriate percutaneously inserted venous catheter 11, aortic ballooncatheter 12, and if this catheter 12 doesn't have provision for arterialblood return, arterial catheter 39 (see FIG. 3). The venous outflow andarterial inflow lumina of the catheters 11 and 12 of the by-pass system8 are of sufficient cross sectional area to achieve standard blood flowsto maintain the patient's systemic circulation during the period ofextracorporeal circulation.

In the case of the use of a single venous double-ballooned catheter 11,as is shown in FIG. 1, the catheter 11 is inserted through the femoralvein preferably. A suitable guide wire is initially inserted and thecatheter 11 is then introduced in known manner under fluoroscopicguidance. The catheter 11 includes a pair of separately inflatableballoons 14 and 15 each connected to a balloon inflation control device(not shown) through suitable lumina in the catheter 11. The balloon 14is adapted to occlude the superior vena cavae 16 while the balloon 15 isadapted to occlude the suprahepatic inferior vena cavae 17. A bloodwithdrawal lumen in the catheter 11 has an inlet orifice 18 flush withthe balloon 14, to avoid venous collapse during blood flow into thecatheter 11, and a series of inlet slots 19 in the inferior vena cavae.Blood drawn into the inlets 18 and 19 enter a common single lumen. Blooddrawn into the by-pass system through the catheter 11 is oxygenated andreturned to the patient in a manner which will be hereinafter described.

A separate lumen in the catheter 11 opens into the right atrium 22through aperture 21 to allow evacuation of blood from the right heartand the infusion of saline to induce topical cooling and/or to improvevisual acuity within the right heart.

In use, after the catheter 11 has been positioned the balloons may beinflated or deflated to vary the rate of venous return to the rightatrium 22 and therefore the degree of decompression of the left heart.Venous drainage may be effected by gravitational drainage or by applyinga degree of negative pressure to assist flow into the pump oxygenator.It will be appreciated that the distance between the balloons 14 and 15will need to be correct for a given patient and this may be assessed byX-ray examination to allow selection of an appropriately sized catheter.Alternatively separate catheters 11b and 11c could be used, as is shownin FIG. 9a, for the inferior and superior vena cavae. The cannula 11bbeing introduced as has been described above and the cannula 11c beingintroduced through the jugular or subclavian vein. It will also beappreciated that for simple operations not requiring complete occlusionof the right atrium it is possible to merely insert a simple catheter 11into the right atrium to draw blood into the by-pass system as is seenin FIG. 2. Positioning under fluoroscopic guidance is not essential inthis case.

The catheter 12 is positioned in the manner described above-with itsfree end located in the ascending aorta 23. The catheter 12 is sopositioned by insertion preferably through the femoral artery 24 and viathe descending aorta 25 as is seen in FIG. 3.

If desired a fluoroscopic dye may be introduced into the aortic root 26through the catheter 12 for accurate positioning of the tip of thecatheter 12 relative to the aortic root 26 and the coronary ostia.

The catheter 12 carries at its free end a balloon 27. The balloon 27 isarranged to be inflated with saline from an inflation control device 28of known type through a lumen in the catheter 12. The device 28 isfitted with a pressure gauge 29 to allow the operator to control theinflation of the balloon 27. The pressure of the fully inflated balloon27 should be of the order of 350 mmHg so as to be sufficient toeffectively occlude the aorta and to prevent the balloon moving whilenot being so great as to cause damage to the aortic wall. The balloon 27should have a maximum diameter sufficient to occlude the aorta and forthis purpose the maximum diameter should be about 35 mm. The balloon 27should have a length of about 40 mm so as not to be so long as toocclude or impede blood flow to the coronary arteries on to thebrachiocephalic, subclavian or carotid arteries. If necessary in anygiven patient the required length and diameter of the balloon may bedetermined by angiographic, X-ray examination or echocardiography and anappropriately sized catheter selected on that basis.

The balloon 27 is preferably connected to the lumen 32 through which itis inflated at the end of the balloon 27 distal to the tip of thecatheter 12 through orifice 31 (see FIG. 5). This allows the tip of thecatheter to contain fewer lumina than the remainder of the catheter.Accommodation of the deflated balloon around the tip of the catheter isthus possible without adding to the diameter of the tip as compared withthe rest of the catheter 12.

The catheter 12 includes a plurality of lumina (see FIGS. 6 and 7). Inaddition to the balloon inflation lumen 32 there is at least a singleventing/cardioplegia lumen 33 of circular cross-section. There may be aseparate and extra circular lumen 34 for instrumentation. If two lumensare present the venting/cardioplegia lumen may be circular or crescentshaped in cross-section (FIG. 6a, 6b). The diameter of the variouslumina should be as small as practicable commensurate with the intendeduse. In addition there may be a continuous lumen 35 through whicharterial blood is returned from the-by-pass. This may flow out of thecatheter 12 through an orifice in the region of the external iliacartery. In alternative embodiments of the invention such as shown inFIGS. 3 and 8 the arterial return lumen 35 may comprise its own catheter39 of known type introduced into the other femoral artery or some othersuitable artery.

In use the catheter 12 is introduced percutaneously by puncture orcutdown as has been described and once blood flow through the by-pass isestablished (including systemic cooling) flows are reduced and theballoon 25 is inflated. Flows are then returned to the operating levelsand a suitable cardioplegic agent is introduced into the aortic root.Once the full volume of cardioplegic agent has been given and cardiacarrest achieved, the lumen is then used to vent the heart. The heart maythen be operated on or examined by insertion of instrumentation 37 suchas a cardioscope or a laser into the heart through the lumen 34 orthrough atrial trocars. Alternatively, with the heart on by-pass asdescribed above the heart can be approached by an open method by anincision other than median sternotomy. Venting of the left ventricle maybe effected by providing an extended cannula 38 projecting from lumen 33into the left ventricle (see FIG. 2) or by simply applying negativepressure to the venting lumen 33 of the aortic catheter. To reversecardioplegic arrest the body is rewarmed and the balloon 27 deflated.Aortic blood is thus allowed to perfuse the heart. Whilst the bodyremains supported by peripheral cardiopulmonary by-pass, the return ofthe heart rhythm is awaited. External defibrillation may be necessary.Weaning from by-pass is then completed in a routine fashion.

I claim:
 1. A system for removing blood from a venous system of apatient and returning oxygenated blood to the patient from anextracorporeal bypass system, the system comprising:a venous cannulaincluding a shaft having a proximal end, a distal end, a bloodwithdrawal lumen, and a first inlet in fluid communication with theblood withdrawal lumen for withdrawing blood from a patient, the bloodwithdrawal lumen being of sufficient size to provide full bypass, theshaft having a length selected so as to extend into at least one of asuperior vena cava and an inferior vena cava of the patient from aperipheral vein; means for occluding a vessel selected from the superiorvena cava and the inferior vena cava of the patient, the vesseloccluding means being mounted to the shaft and being movable between anexpanded shape and a collapsed shape; an arterial cannula having a bloodreturn lumen, the arterial cannula being configured to be positioned inthe patient's vascular system for returning oxygenated blood to thepatient; and an extracorporeal bypass system configured to maintaincirculation of oxygenated blood in the patient when the patient's heartis arrested; wherein the blood withdrawal lumen and blood return lumenare both coupled to the bypass system.
 2. The system of claim 1, furthercomprising:means for occluding an other vessel of the superior vena cavaand the inferior vena cava, the other vessel occluding means beingmounted to the shaft and being movable between a collapsed shape and anexpanded shape.
 3. The system of claim 2 wherein:the shaft includes afluid port and a second lumen, the fluid port being fluidly coupled tothe second lumen and being disposed between the vessel and other vesseloccluding means.
 4. The system of claim 2, wherein:the shaft includes asecond inlet positioned distal of the other vessel occluding means. 5.The system of claim 4, wherein:the second inlet is fluidly coupled tothe blood withdrawal lumen.
 6. A system for removing blood from a venoussystem of a patient and returning oxygenated blood to the patient froman extracorporeal bypass system, the system comprising:a first venouscannula having a first shaft and means for occluding a patient'ssuperior vena cava, the first shaft having a proximal end, a distal end,and a first blood withdrawal lumen, the first shaft having a lengthselected so as to extend into the superior vena cava of the patient froma peripheral vein, the superior vena cava occluding means being mountedto the first shaft and movable between an expanded shape and a collapsedshape; a second venous cannula having a second shaft and means foroccluding the inferior vena cava, the second shaft having a proximalend, a distal end, and a second blood withdrawal lumen, the second shafthaving a length selected so as to extend into the inferior vena of thepatient from a peripheral vein, the inferior vena cava occluding meansbeing mounted to the second shaft and movable between an expanded shapeand a collapsed shape; and an extracorporeal bypass system configured tomaintain circulation of oxygenated blood in the patient when thepatient's heart is arrested; the first and second blood withdrawallumens being coupled to the bypass system.